A concrete product is produced via a process which involves kneading cement, aggregate, water, a dispersant (water-reducing agent) and the like, casting (filling) the resulting mixture into various forms, and curing it therein. If voids, and hollows considered attributable to insufficient filling, are generated on the surface of the concrete product upon removal from the form (demolding) after the curing step and the texture of concrete surface is deteriorated due to other various factors, then the quality of the product is lowered. At present, concrete products having deteriorated surface texture are repaired manually after demolding. However, this operation requires many hands and much time and is thus regarded as one reason for increasing manufacturing costs.
A variety influencing factors on the surface texture of concrete products are known, among which (1) the amount and quality of voids generated during kneading, (2) the strength of concrete at the time of demolding, and (3) concrete viscosity are said to be important factors.
JP-A 2004-2175 proposes use of an admixture containing a polycarboxylic acid polymer and a polyhydric alcohol/alkylene oxide adduct to obtain a cement composition having such viscosity as to make operation easy. JP-A 2006-282414 discloses a strength improver for cement, which contains glycerin or a glycerin derivative and a specific polycarboxylic acid copolymer. JP-A 2001-294466 discloses an admixture for a hydraulic composition, which contains a specific shrinkage-reducing agent and a specific antifoaming agent. JP-A 2007-77008 discloses a surface texture improver containing a specific amide compound and shows a specific polyoxyalkylene compound as a simultaneously used component.